RESUMEN Spanish title: Determinación de un principio activo de Polygonum punctatum; espectros completos de RMN de stigmast-5-en-3¡5-ol (500/125 MHz). El objetivo de este artículo es proveer de información espectral completa de stigmast-5-en-3y3 -ol (1), cuyos otros nombres comunes son: /f-sitosterol, /f-sitosterin, 22,23 -dihydrostigmasterol, and IUPAC ñame: 17-(5-ethyl-6-methylheptan-2-yl)-10,13-dimethyl-2,3,4,7,8,9,ll,12,14,15,16,17-dodecahydro-l-cyclopenta[a]phenanthren-3-ol., and IUPAC ñame: La colección de espectros incluye los estudios HMBC, HSQC and COSY. Los estudios ROESY o NOESY no están contemplados. El compuesto 1 resultó ser el componente mayoritario del extracto alcohólico de Polygonum punctatum (Polygonaceae), especie macrófita nativa de Paraguay con aplicaciones terapéuticas como: hemorroides, abortos y otras. El compuesto 1 fue extraído por maceración en etanol 96° y aislado mediante la aplicación de técnicas cromatográficas. Una investigación bibliográfica permitió establecer una correlación entre la información de la medicina tradicional de la propiedad antiinflamatoria de P. punctatum y el compuesto aislado 1 para el cual una serie de informes sobre sus propiedades farmacológicas permitió afirmar que 1, siendo el componente mayoritario del extracto alcohólico de las raices, es uno de los principios activos de la planta, es decir, el principio anti-inflamatorio. El trabajo espectroscópico y la elucidación estructural condujeron a la identificación del compuesto 1 como /f-sitosterol. La investigación bibliográfica permitió añadir p-sitosterol (1) como un nuevo compuesto en la especie Polygonum punctatum para la cual solo se describió previamente un sesquiterpeno antifúngico potente, polygodial. Con la presente descripción del compuesto 1 en P. punctatum, el número total de metabolitos secundarios y principios activos hasta ahora descritos en la especie alcanza la cifra de dos (según la última revisión bibliográfica sobre el contenido químico del género Polygonum, 2014).

ABSTRACT The aim of this report is to provide full NMR spectra (:H 500 MHz, 13C 125.8 MHz) of stigmast-5-en-3/?-ol (1), whose other common ñames are: /f-sitosterol, /f-sitosterin, 22,23-dihydrostigmasterol, and IUPAC ñame: 17-(5-ethyl-6-methylheptan-2-yl)-10,13-dimethyl-2,3,4,7,8,9,ll,12,14,15,16,17-dodecahydro-l-cyclopenta[a]phenanthren-3-ol., and IUPAC ñame: The spectra set includes HMBC, HSQC and COSY studies. ROESY or NOESY studies were excluded. Compound 1 is found to be the major component of the alcoholic extract of roots of Polygonum punctatum (Polygonaceae), a macrophyte native species of Paraguay with varied therapeutic applications like anti-inflammatory among others. Compound 1 was extracted by maceration in EtOH 96° and it was isolated by using chromatographic techniques. A bibliographic research allowed to establish a correlation between traditional medicine information of anti-inflammatory property of P. punctatum and the isolated compound 1 for which a series of reports about its pharmacological properties permitted to affirm that 1, being the major secondary metabolite in the alcoholic extract of roots, is one of the active principies of the plant, namely the anti-inflammatory principie. The spectroscopic work and the structural elucidation permitted the identification of compound 1 as /f-sitosterol. The bibliographic research allowed to label /f-sitosterol (1) as a new compound in the species P. punctatum for which only polygodial, a potent antifungal sesquiterpene, was previously described. With the present reporting of compound 1 in P. punctatum, the total number of secondary metabolites and active principies thus far described in the species reaches the cipher of two (according to the newest bibliographic review on the chemical content of the Polygonum genus, 2014).

The intramolecular Friedel-Crafts acylation reaction of 3-arylpropanoic acids to give 1-indanones can be effected in good yields under mild conditions (room temperature) by using niobium pentachloride. Our results indicate that NbCl5 acts both as reagent (to transform carboxylic acids into acyl chlorides) and as catalyst in the Friedel-Crafts cyclization.

A hexa-oligosaccharide was obtained by partial acid hydrolysis from botryosphaeran, an exopolysaccharide (EPS) β(1→3; 1→6)-D-glucan type, produced by the ascomyceteous fungus Botryosphaeria rhodina. The oligosaccharide was purified by gel filtration and charcoal-Celite column chromatography and the analysis was followed by HPAEC/PAD. The structure was determined by NMR spectroscopy and mass spectrometry, which showed that the oligosaccharide consists of six β-D-glucopiranosyl units O-6 substituted (gentiohexaose).

A computational quantum chemistry experiment is described of Diels-Alder reactions between 2-cycloenones and cyclopentadiene. The effects of FMO-Frontier Molecular Orbitals (HOMO-LUMO) and of the withdrawing nature of substituents at the C=C bond of cycloenones were evaluated. The calculations were made using HF/STO-3G and B3LYP/6-31+G(d,p) methods. The FMO based indexes are in agreement with the experimentally observed reactivity order. NBO - Natural Bond Orbitals - analysis was used to ascertain the effect of C=C substituents on the dienophile reactivity.

Complex ¹H NMR spectra multiplets that cannot be easily understood by simple inspection are rather frequent in the daily work of the organic chemistry analyst. The multiple and excellent new techniques available from modern instruments usually provide satisfactory solutions, but there are still many cases where a simulation is necessary, at least to obtain a final confirmation. It is extremely convincing to see that a graph, obtained by calculations with chemical-shift and coupling-constant values only, can be virtually identical to the experimental spectrum. This paper describes a computer program to make such calculations. The program is free and can be downloaded from <A HREF="http://artemis.ffclrp.usp.br/NMR.htm">http://artemis.ffclrp.usp.br/NMR.htm</A> (click on SimEsp_NMR_Compil.zip). All routines are also available and may be used without any restrictions. The paper includes a fairly detailed discussion about how the calculations are made.

A 1,2-secomicrominutinina (25) racêmica foi sintetizada empregando-se a reação de cicloadição intramolecular de um alceniloxiceteno, preparado a partir do correspondente tosilato. O alceniloxiceteno sofre reação de cicloadição [2+2] intramolecular originando uma benzociclobutafuranona tricíclica (16) que, por oxidação de Bayer-Villiger, fornece uma benzofurofuranona (17). Reação desta última com propiolato de metila, catalisada por trifenilfosfina, produziu o derivado de éster cinâmico (25).

The racemic 1,2-secomicrominutinin (25) was synthesized employing the intramolecular cycloaddition reaction of an (alkenyloxy)ketene, prepared from the corresponding tosylate. The (alkenyloxy)ketene undergoes intramolecular [2+2] cycloaddition to give tricyclic benzocyclobutafuranone (16), which by Baeyer-Villiger oxidation gives a benzofuranofuranone (17). Reaction of the latter compound with methyl propiolate, catalyzed by triphenylphosphine, produced the cinnamic ester derivative (25).

In this paper we describe three computer programs in Basic language about the Fourier transform (FFT) which are available in the Internet site http://artemis.ffclrp.usp.br/SoftwareE.htm (in English) or http://artemis.ffclrp.usp.br/softwareP.htm (in Portuguese) since October 1998. Those are addresses to the Web Page of our Laboratory of Organic Synthesis. The programs can be downloaded and used by anyone who is interested on the subject. The texts, menus and captions in the programs are written in English.

In this paper we describe the reduction by NaBH4 of some cyclopentanones containing an oxygenated function at the side chain position beta to the carbonyl group, both in the presence and in the absence of CeCl3. Some suggestions for the rationalization of the results are discussed, considering the stereochemical course of the reactions.

In this paper we describe how to make a very simple stereoscope for observation of molecular models produced by several recent computer programmes. With this instrument, constructed essentially with four mirrors, the chemist can visualize molecular models in three dimensions directly from the personal computer monitor screen.